AcquisitionChain add a scan property
When using a ChainIterationPreset one can need to access some parameters(count_time...) from the scan.scan_info within the get_iterator, e.g:
def get_iterator(self, acq_chain):
scan_info = acq_chain.scan.scan_info
count_time = scan_info['count_time']
npoints = scan_info['npoints']